The Niles Audio SSVC-2 Two-pair Speaker Selector is a combination speaker selector and volume controller. It allows you to connect multiple pairs of speakers to your stereo receiver or amplifier and adjust the volume of any pair independently. Additionally, you can choose to listen to any pair of speakers, or any combination of pairs simultaneously. You don't have to worry about overloading your amplifier. The SSVC series uses impedance magnification to keep your amplifier running safely, even with all speakers playing. A perfect application for the SSVC series is individually controlling speaker on/off and volume adjustment for multiple pairs of speakers: one pair in the room with the main stereo system and all other pairs at remote locations. The SSVC series adjusts the volume of the speakers connected to it by attenuating the amplifier signal. Niles Audios volume controls use autoformers instead of L-pads for the volume controlling element. This assures minimal internal power dissipation with virtually no power wasted as heat. Also available are Four Pair or Six Pair speaker selectors with volume controls, each sold separately.